The present invention relates to a broadcast receiving device for receiving broadcasts such as digital broadcasts, and a stream output device for recording and playback of stream data such as digital video/audio signals.
With the recent development of digital video signal processing, settop boxes (STBs) for reception of satellite broadcasts, digital AV apparatuses such as digital VTR (DVTR) for recording and playback of digital broadcast programs, and disk recorders have been manufactured successively. As a digital interface which is most suitable for transmitting video/audio signals while keeping the digital signal format between these digital AV apparatuses, a high speed serial bus (hereinafter referred to as a “1394 bus”) is available as defined by IEEE 1394 standards. Stream and control commands can be simultaneously transmitted/received on the 1394 bus, and as stream transmission/reception control and control commands, IEC61883 standards and the AV/C command set are provided.
As a technique for prevention of the unauthorized copying of contents, a DTCP (Digital Transmission Contents Protection) specification has been adopted in the 1394 bus. In the DTCP specification, the video/audio stream is assigned with copy control information describing conditions for copying and data copying is sorted into any of three modes of “copy free” (unlimited copying), “copy never” (copying prohibited), and “copy one generation” (single copying enabled). The recording apparatus such as digital VTR is permitted to receive and record only a stream subject for “copy free” or “copy one generation.” As for the latter, after recording a stream subject to “copy one generation”, the copy control information is changed to “no more copies” (copying disabled), thus inhibiting other recording apparatuses from recording the contents any further.
On the other hand, a stream recording/playback apparatus such as a so-called hard disk drive (HDD) recorder has recently become available for recording video/audio stream data using a hard disk drive (HDD). Due to the fact that the disk capacity in the apparatus in the case of a HDD recorder is limited, if the free disk space decreases, the user must transfer the contents to be stored to a VTR or optical disk device to be stored in a storage medium such as a tape or optical disk.
For this reason, in the DTCP specification, the contents once recorded in the recording medium as “no more copies” are copied to another recording medium and consequently deleted from the original recording medium or playback is disabled. This function of transferring the contents is defined as a “move function”. This move function can be executed only with a built-in or digitally connected single recording medium and it is prohibited that the contents with a length exceeding 1 minute are in a playback-enabled state at both the move source device and the move destination device during the move operation. A technology for mounting the move function was described in the following patents: